The study of syntactic development in children, for all intents and
purposes, is reducible to a single minded inquiry into how the very young child
(implicitly) knows to distinguish between lexical stems and functional affixes. Hence, the overriding question burning in the minds
of most developmental linguists is morpho-phonological in nature. For instance,
it would seem that the child must at least know (a priori) the stem before she can then engage in a dual-track
process by which ambient separation of the morpho-phonological distinction
attributive to past tense is carried out, say, between the paradigmatic
representation of the English word play vs. play-ed /ple-d/ (a dual processing which provokes separation of the /play/-stemand
the /d/-affix). Otherwise, it
could be conceivable for the young child that the pair play-played
would represent altogether two different lexical stems, and, stored as such,
reflect two distinct though relatively similar semantic notions (a single
processing): perhaps not unlike what we do find regarding derived words where
an otherwise 'two-morpheme' analysis of [teach]-{er} is
processed (tagged, stored and retrieved) as a 'single-morpheme' stem [teacher], similar to how the word[brother]is stored. (See Clahsen et al. 2001).

In this paper, we limit our discussion to exploring
the developmental onset of inflection in child language acquisition and to
seeing if such a maturational-based interpretation of the Dual Mechanism Model
(DMM) is justified. We believe the findings provided in this study coincide
with a maturational-based interpretation consistent with the Dual Mechanism
Model, a processing model which seeks to distribute specific language
processing tasks related to stem+affix separation to certain areas of the brain-inflection
being just one such processing task. In general, the notion of a 'maturational
DMM' relies heavily on our current understanding of brain-to-language
processing as well as on more general hemispheric/task-oriented notions which
lie behind human brain development. For instance, if-as our current
understanding of the brain-language relation leads us to believe-the idea that
the more substantive elements of language (i.e., lexical stems and derivational
formations) are rather pinned to associative-sensitive regions of the brain is
correct, coupled with the growing sentiment that there resides a separate
region of the brain which partakes in affix partition, then a maturational view
of brain-language development would naturally predicate chronological asymmetries
between associative stem and rule-based affix/inflection onsets.

Overall, we conclude that the child language data
presented herein indeed do demarcate a dual stage in the acquisition of child
English inflection, and that the data could be characterized in two ways: (i)
that children gradually gain access to and eventually make tacit use of innate
syntactic knowledge, allowing them instinctively to know to separate stem from
affix-leading to a Gradual Development Hypothesis which shows developmental asymmetry between the
acquisition of lexical vs. functional categories (Radford 1990)-and (ii) that
such prima facie knowledge
naturally arises from The Dual Mechanism Model, a processing model that offers the best of both
worlds in that it can account for both how the child comes to 'know' lexical
stems in the first place, and subsequently, how such stems come to be
distinguished and project morpho-phonological material leading to stem vs.
affix separation.

Two-and three year old children gradually go through a
stage during which they sporadically omit possessives 's, so alternating
between saying (e.g.) Daddy's car
and Daddy car. At roughly the same
age, children also go through a stage (referred to by Wexler (1994) as the optional
infinitive stage) during which they
sporadically omit the third person singular present tense +s inflection on
verbs, so alternating between e.g. Daddy wants one and Daddy want one. The question addressed in this paper is whether
children's omission of both inflections is related and potentially tied to
processing factors as determined by the DMM. The question is explored in
relation to data provided from a longitudinal case study of one child.

By the very definition of the Dual Mechanism Model,
children 'know' that Inflected forms are not lexical since such forms are conceptualized and
generated in a separate processing modular. The DMM maintains that a clean
separation takes place between the lexical stem and the affix-a stem is 'meaning based' and thus is believed to be housed in the
temporal-lobe region of the brain (associative-based ), while the affix is
'abstract' and thus is equated to more formal processing located in the
frontal-lobe region (rule-based). The lexicon lists only lexical items (stems)
while functional items (affixes) are added at a second stage in the numeration.
The DMM credits the Brain/Mind with having two fundamentally different cognitive
modes of language processing-this dual mechanism has recently been reported as
reflecting inherent qualitative distinctions found between (i) regular verb
inflectional morphology (where rule-based stem+affixes form a large contingency) and (ii) irregular verb
constructions (where full lexical forms seem to be stored as associative
chunks). The Language Faculty thus
provides us with two ways of symbolic representation. (See Pinker 1999, Clahsen
1999 for a review of the DMM).

Radford and Galasso (1998), Galasso (1999/2003c)
Radford (1999, 2000, 2004) provide English data showing that children show
asymmetric development regarding the complete formation of the dual mechanism
model-i.e., while the mechanism for word/stem acquisition may be fully (or at
least partially) developed from the outset of early child speech, the more
formal mechanisms dealing with affix structures and the stem+affix separation
involves a more protracted development. The data provided indicate that English
children may initially enter into a 'No Agreement' / 'No Inflection' stage-one
of acquisition during which they completely omit (rule-based) Inflections.

The first aspect of inflection we turn to is the
potential syntactic relationship that holds between the acquisition of
possessive 's and the third person singular +s. Prior to age 3;2 the data show no
attested use of either nominal possessive 's or verbal inflected +s in
obligatory contexts.

(1) OCCURRENCE IN
OBLIGATORY CONTEXTS

AGE 3sgPres
s Poss
's

Stage-1 2;3-3;1 0/69
(0%) 0/118
(0%)

Stage-2 3;2-3;6 72/168
(43%) 14/60
(23%)

(2)Stage-1: 'No AGReement-No INFLection' (Radford
& Galasso 1998)

Possessives: That Mommy car. Me dolly. No
baby bike. Him name.

Have
me shoe. *Iwant me
bottle. It me.

Question: Where
Daddy car? This you pen? What him doing?

Declarative: Baby
have bottle. Car go. Me wet. Me playing. Him dead

*(Iwant
examplesare analyzed as formulaic since no other supportive
material

providing
for a functional analysis of nominative case is found in the relevant stage).

The OI stage (as suggested by Wexler 1994) would simultaneously
incorporate both data sets as described in his initial Optional Infinitive
stage-1. Radford & Galasso, however, make a clear demarcation between the
two stages, with the complete absence of any optional functional projections
for their stage-1. Overall, children in this initial stage-one of pre-syntactic
development are forced into projecting very limited structure. For instance,
(and this is not an exhaustive list):

(4)
(a) Possessive projections, which rely on an AGReement relation with a nominal
INFL, must default to an objective case (e.g. Me show, Mommy car);

(c) Subjects, which rely on an AGReement with a verbal
INFL, must default to having an objective case (e.g., Me wet).

Consider the syntactic structures below pairing the two data sets, with
stage-one showing no inflectional phrase (IP) agreement. Regarding (4a) above,
we follow Kayne's analysis (1994: p.105) in assuming that nominal inflected
structures such as Mommy's car would
contain an IP projection with the structure (5) below (with (5a) having an I
nominal head and (5b) a verbal head):

Radford & Galasso (1998) suggest that both nominal
possessive 's and verbal 3sgPres +s are indeed reflexes of the same agreement mechanism.
Such a relationship would be expected under a maturational-based interpretation
of the DMM given the assumption that both INFL-related structures are
theoretically derived from the same unique area of the brain which is
ultimately responsible for affix generation and separation. In support of this
hypothesis, Schütze and Wexler (1996), Schütze (1997) similarly suggest that
both instances of Non-Inflection (i.e. zero possessive 's and verbal +s) may be
the singular result of the head of I being underspecified (or potentially, as
this study shows, non-specified)-the differing results amounting to whether or
not it is a verb or a nominal element that gets underspecified is merely seen in
respect to the kind of specifier-agreement features the head carries. In other
words, what we are espousing here is a more unifying approach to inflection in
two fundamental ways: first, in the sense of Kayne (above), that IP no longer
need be restricted to serving verbal elements only and that nominal elements as
well may potentially be expressed as housed within IP; and second, that the
mechanism behind IP may in fact reduce to a more unifying process by which new
interpretations of the DMM along with maturational hypotheses of brain-to-language
development can now enter into the equation. Overall, we could draw similar
conclusions regarding the full extent of how inflections manifest across the
board pertaining to both nominal and verbal heads-showing a Pre-INFL/AGR stage
exhibiting the limited INFL and AGR structure discussed in (4). For the remainder
of this paper, we'll take each potential INFL structure in turn and follow its
development as indicated by the data.

(6) POTENTIAL INFL
STRUCTURES

Structure: Stage-One / -AGR Structure:
Stage-Two /+AGR

(a) Poss: * [IP
Mummy [I {-agr}-ø] car] [IP
Mummy [I {+agr}'s] car]

[IP Me [I {-agr}] dolly] [IP
My [I {+agr}] dolly]

(b) Case: [IP Him [I {-agr}] dead] [IP
He [I {+agr}'s] dead]

[IP Me [I {-agr}] wet] [IP
I [I {+agr} 'm] wet]

(c)
Verb: [IP Baby [I
{-agr} have]]... [IP
Baby [I {+agr} has]]...

[IP Car [I
{-agr}go -ø]] [IP
Car [I {+agr} go-es]]

I believe it is worthwhile to note that similar findings are born out
and widely attested in the literature and are consistent with the general
notion that language acquisition involves some sort of incremental
feature-building (Radford 2000)-viz.,
the notion that if language does proceed in an incremental way, then it should
be of little surprise that the more robust and primitive aspects of a language
should come on-line and precede more abstract aspects of language-specifically,
the default {-agr} feature projections attributed to the VP (by default) come
on-line before {+agr} projections attributed to the IP. (Galasso (2003c)
describes such early stage-one structures as reduced to simple lexical VPs and
NPs). This gives us the flavor of saying that a maturational scheduling is behind the chronological ordering of features (much
in the spirit of the Brown studies (1973) which sought to show a time-line of
affix morpheme development-moving from potentially viable semantic-based
participle forms {en}, {ing} through to true rule-based inflectional forms 3PSg
{s}, Possessive {s}, Past Tense {ed}.

Next, we turn to the child's earliest use of Case (6b)
with respect to overt Copular sentences. If we assume (following Radford 1999)
that children build-up morpho-syntactic features (relating to AGR/INFL)
incrementally, then, at least hypothetically speaking, there could be a stage
during which the functional I head could go non-specified. This pre-INFL stage
shows itself in the data when we examine the development of case. Returning to
the axiom drawn in (4c), we can provide a straightforward account of why two-and
three-year-olds alternate between agreement-less forms like Meplaying
and agreeing forms I'm playing. The
INFLectional relationship binds Pro(nominal) Case to the AGR features of the
head in I. The two types of clause are characterized below:

A chronological development is observed to hold
between the Nominal INFL of Case on one hand and the Verbal INFL of
Tense/Agreement on the other. The table below shows the relative frequency of
I and me subjects in copular sentences. (Prior to age 2;6, Nom
Case is virtually non-existent with the earliest forms showing as unanalyzed
chunks):

The agreement
relationship that binds the +Agr head to Pron(nominal) Case could be argued as
having the same structure found in (6):

(10) (a) [IP Me [I {-agr} ø ] wet] (b)
[IP I [I {+agr} 'm ] sick]

In (10b) above, the head of I is marked +AGR and so carries all the
relevant syntactic features associated with the Spec-Head configuration (i.e.,
an overt copular maintaining present Tense and Case features assigned to an
overt nominative pronoun). Similar asymmetries of development along with parallels
of structure pertaining to possessors likewise manifest in the data. If we look
at the earliest first person singular possessor structures, we find adhering to
(4a) that Objective me possessors
dominate early on with only the genitive case my forms at first gradually emerging, and then only being
mastered over a protracted time of syntactic development. (Prior to the age
2;6, all potential possessor forms carry the default objective case).

(11)FREQUENCY OF FIRST PERSON/SINGULAR POSSESSORS

AGE OBJECTIVE
ME GENITIVE
MY/MINE

2;6-2;8 53/55
(96%) 2/55
(4%)

2;9 11/25
(44%) 14/25
(56%)

2;10 4/14
(29%) 10/14
(71%)

2;11 5/24
(21%) 19/24
(79%)

3;0 4/54
(7%) 50/54
(93%)

3;1-3;6 6/231
(3%) 225/231
(97%)

When comparing the development of subject-verb
agreement to that of possessor agreement, the data suggest that subject-verb
agreement emerges sooner than possessor agreement. It is suggested in Radford
and Galasso (1998) that this asymmetry in the development of an otherwise
unique agreement mechanism may be the result of overt vs. covert features that
get encoded on INFL. It may be that the earlier subject-verb agreement is
triggered by the overt use of {'m/am}
encoded in the head of the verbal I. Possessors, on the other hand, may rely on
an invisible trigger mechanism in the sense that there is no overt feature
encoded on the head of the nominal I. If this generality is anywhere on the
right track, one assumption that could have universal consequences for child
language acquisition may be that children's INFL mechanism is triggered by the
relevant overt head features (much in accordance with Schütze and Wexler's
position stated above).

(12) FREQUENCY OF
SECOND PERSON POSSESSORS

AGE YOU YOUR

3;2-3;4 14/16
(88%) 2/16
(12%)

3;5 7/34
(21%) 27/34
(79%)

3;6 2/29
(7%) 27/29
(93%)

(13) (a) No you train
(= It's not your train). No you baby. This is you pen. (3;2)

(b) That's your car. Close your eyes. Where's your friend? (3;5)

(14) (a) [IP You [I {-agr} ø] train] (b)
[IP Your [I {+agr} ø] car]

Third person singular forms him/his appear in the data at around the age of 3;6 10/13
(77%) of the relevant structures have an objective him possessor, the remaining 3 (23%) having a genitive his possessor.

(15) (a) It's him
house. It's him hat. (x2) Him eye is broken. Go to him house.

(b) What's his name? (x3)

(16) (a) [IP him [I {-agr} ø] house] (b)
[IP his [I {+agr} ø] name]

When comparing the data (up to age 3;6) of third person singular
subjects with that of third person singular possessors, we find a parallel
pattern of development showing the default objective case him throughout. This finding would be consistent with the
view that at the early stage of syntactic development, the head of INFL goes
unspecified for both nominal (genitive) and verbal (subject) INFL heads in
accordance with (4) above.

Typical copular clauses with third person singular
subjects are given below (taken from data files reaching age 3;6):

(17) (a) Here's him. Where's him? Him is alright. Him
is my friend.

Him is hiding. Him is a big woof-woof. What's him
doing?

Where's him going? Him dead. Him my friend. Him blue.

(b) He's happy. He's bad.
He is a bad boy. He's in there.

He happy. He a elephant.

25/32 (78%) of the copular sentences with third person singular
subjects have objective him
subjects. This figure parallels him
possessors which showed a similar 77% rate of usage. Again, these finding are
consistent with the view that INFL should be reconsidered and rather thought of
in a more holist manner, pertaining to the agreement mechanism that brings
about nominal and verbal inflection. Moreover, in refashioning this holistic
status of INFL, a single maturational trigger having to do with
inflection/agreement comes to mind with the claim that it is responsible not
only for the systematic failure and/or gradual development of both nominal and
verbal INFL (on the one hand), but also may aid developmental linguistics in
understanding more global issues of abstract grammatical functions in child
language acquisition (on the other).

We can summarize the data thus far: we find an
interesting parallel between the development of both nominal INFL (yielding
objective possessor me/you/him
forms) and verbal INFL (yielding objective me/him subjects). These reported INFL non-specifications are
produced well up to age 3;6, after which time full mastery of INFL takes hold
(for complete data analyses, see Galasso 2003c). Furthermore, (following Kayne)
by granting the possessive 's
structure as having the status of a possessor-agreement inflection, we can
better understand the obvious parallels drawn here between the development of
s-possessives and s-verbal inflections. These parallels are summed-up as
follows: just as possessor agreement fails to be marked early-on in the files
(e.g., Baby bottle, Him name), a
result of the holistic failure of the (nominal) INFL mechanism, so too do
subject-verb agreements fail to get marked (e.g. Him is my friend. Where's
him going?), a result of the holistic
failure of the (verbal) INFL mechanism. In conclusion, what the data suggest is
that there is a three-stage model of the acquisition of inflection (and not a
two-stage model, pace Wexler's
OI-stage). The first stage in the data provides us with a glance at what a true
pre-INFLection stage might look like, a stage characterized by all the classic
hallmarks of a lexical stage-one (cf. Radford 1990). Any notion of an Optional
Infinitive/Inflectional stage, as these data suggest, must be relegated as
having the status of a 'stage-two' in the syntactic development of a child,
where INFL related material gradually comes on-line and begins to take-on
optional projections. In the final analysis, these findings correspond with both
a maturational and holistic treatment of INFL-both of which are compatible with
a maturational DMM.

Overall, the data presented in this study suggest that
an interesting and previously unreported symmetry holds between the developments
of subject-verb agreement structures on one hand and possessor+noun structures
on the other. The data show an initial no inflectional stage-one followed by an optional inflectional stage-2. The symmetry is explained under the
hypothesis that grants INFL a holistic status. The data reveal that leading up
to age 2;6, the utterances are completely void of INFLection. At around age
2;6, the data reveal an optional inflectional stage at which alternations
emerge between forms like me car /
my car, Him dead / He is dead, and Baby have bottle / Baby hasbottle, etc.

Notes

The data in this paper was first presented to the annual convention of
the American Speech and Hearing Association in November 1997 by Andrew Radford. This revised version
of the text was presented at the CLRF-2004 at Stanford. I would like to thank
Eve Clark (Stanford) for allowing me to present this paper.

Following Schütze and Wexler (1996), the notation [+agr] is used as an
informal way of indicating that INFL carries a set of person/number features
which agree with those of its specifier, and the notation [-agr] serves to
indicate that the relevant features are un(der)specified in some way.